1. Field of the Invention
The present invention relates to a top roller apron for guiding a cast strip under a mold with a slight clearance in a continuous casting assembly.
2. Description of the Prior Art
A top roller apron in a conventional continuous casting assembly is composed of a back face frame, an inside face frame and a pair of narrow-face frames. In the case of a two-faced roll type, a roll-bearing housing assembly is attached to the back face and inside face frames and a shim is disposed under the bearing housing, whereby each roll is so adjusted as to lie along back face side and inside face side circular arcs (see, for example, U.S. Pat. No. 4,131,154 corresponding to JP-B2-No. 3453/1982).
In the case of a four-faced roll type, a roll-bearing housing assembly is attached to an additional pair of narrow-faced frames and a shim is disposed under the bearing housing, whereby the level of each roll is adjusted. The frames are each positioned with a key and are fixed in the form of a framework through tie rods, and the roll gap is adjusted with a shim disposed between the paired narrow-faced frames and the adjustable frame.
In the top roller apron there occur various phenomena such as slag inclusion, abnormal wear and corrosion caused by the influence of flux and roll deformation, as well as break-out damage. As a result, it is sometimes necessary to replace only one roll before replacement of the entire top roller apron.
At the time of such maintenance it is necessary to first disassemble all the frames and thereafter replace the roll in question. Thus the operation is particularly troublesome since disassembly results in a potential loss of alignment of the rolls. Moreover, since the alignment of the conventional top roller apron is adjusted with a shim disposed between the apron and a support bed of the equipment, it is necessary to lift the top roller apron from the support bed, but this operation creates difficulties because of limited working space.